Embodiments of the present invention relate generally to contactless power transfer systems and more particularly to systems for contactless power transfer between components wherein at least one of the components is rotating.
Mechanical slip rings are often employed to transfer electrical power between rotatable components of machines. Slip rings are metal rings mounted on rotatable components of machines which are in electrical contact with stationary components of machines through conductive brushes of the stationary contacts. Slip ring sizes and materials are application specific, and regular maintenance of slip rings is required to ensure uninterrupted operation of the machine as mechanical damage may occur.
Rotary transformers are alternatively used in some applications to provide contactless power transfer between rotatable components. A rotary transformer includes two rotating inductive coils and works on the principle of induction coupling to transfer power from one coil to another. Rotary transformers operating at power frequencies of 50 Hz or 60 Hz are bulky and heavy. One way of reducing the size of a rotary transformer is to operate the transformer at high frequencies and couple resonant tank circuits to primary and secondary windings of the transformer.
However, upon reduction of rotary transformer size, the efficiency of the rotary transformer becomes more sensitive to changes in the gap between the primary and secondary windings of the transformer or load variations in the machine. In other words, any change in the air gap between the two coils reduces the magnetic field coupling and results in reduced efficiency of the rotary transformer.
Hence, there is a need for an improved system and method to address the aforementioned issues.